by Tristram Bainbridge, Furniture Conservator
A brightly-coloured Korean lidded box, made in the nineteenth century from reverse-painted horn in the late Choson dynasty (1392-1910), was treated for the Lustrous Surfaces display: a cross-cultural showcase of Asian lacquer throughout the Museum (Figure 1). Small panels of ox horn were painted on the reverse and adhered to the box’s wooden substrate with a protein-based animal glue. The panels each have a distinct scene of animals and flowers, each one variously representing longevity and good fortune. Although not made from lacquer, with its glossy surface it forms part of the East-Asian artistic tradition which employs a large range of materials and techniques in the creation of decorative arts. Asian lacquer work can be characterised by its lustre and the use of horn allows the craftsman to create a shiny surface, not limited by colour palette or lacquer technique. The technique is called hwagak in Korean, literally translated as ‘brilliant horn’.
The translucent property of horn has been well known around the world for centuries; in Europe, lanterns were commonly made from horn panels and were sometimes referred to as ‘lanthorns’. Horn appears in boulle marquetry from the seventeenth century, often with a painted paper backing. The technique for creating usable panels has changed little. The tip of the horn is cut off then the cone-shaped piece is cut open along its length and boiled in water for hours to soften it. Direct heat from a stove or burner is then applied to the surface to soften it further and the cylindrical piece is opened out and flattened using tongs. The flattened piece of horn, around 10 mm thick, is then cut in two along its thickness. The cut pieces are further reduced in thickness with files and other grinding tools. The surfaces are scraped smooth and the final thickness can be around 0.5 mm. Korean ox horns are relatively short, so the panel dimensions on this box are around 100 x 65 mm.
The paint is proteinaceous, traditionally made from the swim bladder from the brown croaker fish (Sciaenidae sp.) and skin from the walleye pollock (Gadus chalcogrammus). 1 To adhere the panels to the box, animal glue would have been applied to the wooden substrate, allowed to dry and then re-activated with a hot iron when the horn piece was applied. This would have prevented the paint layer from being disrupted by wet animal glue.
Treatment was carried out on this box to re-adhere the lifting horn decoration. Like wood, horn is hydroscopic and anisotropic: it absorbs atmospheric humidity, shrinking and expanding with fluctuations in relative humidity. Some of the horn panels had fine parallel cracks and larger cracks that had caused a loss of material. The combination of movement in the wooden substrate and in the horn resulted in around 80 loose areas. The main challenge in re-adhering translucent material is in the selection of an adhesive that does not disrupt the painted decoration or cause visual problems with chromatic change or saturation. The protein-based paint was likely to have been sensitive to aqueous adhesives and testing revealed the paint layer was disrupted by polar solvents. Paraloid B-72 15% w/v concentration in xylene was trialled and no negative interactions were noted. The B-72 mixture was injected under the lifting horn and massaged further under using bamboo spatulas.
Various clamping methods were used, including deep throated ‘G’ clamps and Berna Multiclamps (Figure 2). The clamping pad used 3mm clear acrylic squares to spread the clamping load with a soft silicone sheet (20 Shore A) to conform to the uneven surface.2 To clamp the edges of the box silicone putty cauls were made using a harder addition cure dental putty (60 shore A). These were moulded directly on the area to be clamped with a thin polythene barrier layer between the silicone and the object.
A similar scenario had been encountered when treating painted paper-backed horn on marquetry objects for the Europe 1600–1815 galleries. The early eighteenth-century desk (372-1901, Figure 3) has marquetery with horn, turtleshell, brass, copper and mother-of-pearl. Several areas of the horn veneer were lifting and there was adhesive failure between the painted paper and the horn, as well as between the paper and the substrate. Any wet method for re-adhering caused colour change and saturation. The horn was re-attached using cast films of isinglass. These were inserted under the horn, softened using a localised humidity chamber (made from a small plastic dish and damp cotton wool), and further warmed with a Preservation Pencil that directed warm (60oC) moist air to the surface. The horn’s surface was protected with polyester Bondina and blotting paper and heated MDF blocks were then used to clamp the horn in position.
Horn has been valued by craftsmen for its translucency, but as these treatments show, this property can be a challenge for the conservator when it comes to treating without causing visual change to the object.
Many thanks for support from the Overseas Korean Cultural Heritage Foundation, Mr. Yang Seok Joong, lacquer and furniture master and Mr Kim Kyoungsu, lacquer conservator at the National Museum of Korea. Thanks also to Rosalie Kim, V&A Samsung Curator of Korean Art; Alex Owen, Furniture Conservator who developed the treatment for the Hwagak box, and Andrew Thackray, Furniture Conservator who treated the marquetry desk.
- Lee Jae-man, Korean Hwagak master interviewed by ArirangTV in 2014, https://www.youtube.com/watch?v=5Y5AzJZu6No (accessed 20/02/18).
- Bainbridge, T., et al. Goberge, Shimbari, Go-Bars: The Use of Flexible Sticks for Clamping in Journal of the American Institute for Conservation, Vol. 54, Iss. 2, 2015.